Heat exchanger

ABSTRACT

The housing of the heat exchanger has an elongated body section. Located within the body section are two axially-spaced radiallydisposed header plates with a plurality of axial apertures. Extending through the apertures are a plurality of elongated tubes. The body section and the header plates are compressed radially inwardly to effect a tight engagement between the body section and the header plates and between the header plates and the tubes. Brazing material seals the header plates to the body section and seals the tubes to the header plates.

United States Patent v [191 Tramontini [451 Feb. 4, 1975 HEAT EXCHANGER [75] Inventor: Vernon N. Tramontini, Indianapolis,

Ind.

[73] Assignee: Stewart-Warner Corporation, Chicago, Ill.

[22] Filed: Aug. 27, 1973 [21] Appl. No.2 391,540

[52] 11.8. C1. 165/158, 29/157.4 [51] Int. Cl F28b 9/14 [58] Field of Search .l 165/162, 158, 156;

29/1573 R, 157.3 A, 157.3 C, 157.3 D, 157.4

[5 6] References Cited UNITED STATES PATENTS 2,577,124 12/1951 Newcomer 29/157.3R

3,223,154 12/1965 Goebel ..165/l58 Primary Examiner-Charles J. Myhre Assistant Examiner-Theophil W. Streule, Jr.

[ 7] ABSTRACT The housing of the heat exchanger has an elongated body section. Located within the body section are two axially-spaced radially-disposed header plates with a plurality of axial apertures. Extending through the apertures are a plurality of elongated tubes. The body section and the header plates are compressed radially inwardly to effect a tight engagement between the body section and the header plates and between the header plates and the tubes. Brazing material seals the header plates to the body section and seals the tubes to the header plates.

3 Claims, 7 Drawing Figures 1 HEAT EXCHANGER BACKGROUND OF THE INVENTION One general type of heat exchanger comprises a housing, a pair of axially-spaced header plates with a plurality of axial apertures, and a plurality of elongated tubes extending through the apertures. Heat transfer is effected between one fluid flowing through the tubes and another fluid flowing about the tubes intermediate of the header plates.

To prevent the two fluids from intermixing, the header plates must beproperly sealed to the housing, and the tubes must be properly sealed within the apertures of the header plates. I-Ieretofore, the assembly of these parts to accommodate sealing, and the provision of seals at the indicated locations, have been expensive and/or ineffective.

SUMMARY OF THE INVENTION Like the general type of heat exchanger referred to above, the heat exchanger of the present invention comprises a housing with an elongated body section, a pair of axially-spaced header plates with a plurality of axial apertures, and a plurality of elongated tubes extending through the apertures.

For ease of assembly, the header plate apertures initially are larger in diameter than the tubes, and the header plates initially are smaller in diameter than the inside of the body section. Then, to accommodate the use of an inexpensive brazing material such as copper, which requires a very close fit between parts being brazed, the body section and the header plates are compressed radially inwardly to effect a tight engagement between the body section and the header plates and between the header plates and the tubes. Finally, brazing material is applied and serves to seal the header plates to the body section and the tubes to the header plates. I

The resultant heat exchanger unit is relatively inexpensive to fabricate and is securely sealed at the required locations. I

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of the heat exchanger of the present invention;

FIG. 2 is an elevational view of one end of the heat exchanger of FIG. 1;

FIG. 3 is an elevational view of the other end of the heat exchanger of FIG. 1;

FIG. 4 is a transverse sectional view taken substantially along the line 44 in FIG. 1 looking in the direction indicated by the arrows;

FIG. 5 is a longitudinal sectional view taken substantially along the line 5-5 in FIG. 4 looking in the directionindicated by the arrows;

FIG. 6 is a transverse sectional view taken substantially along the line 6--6 in FIG. 1 looking in the direction indicated by the arrows; and

FIG. 7 is a partial sectional view taken substantially along the line 7 7 of FIG. 4 looking in the direction indicated by the arrows, and illustrates the initial clearance between the parts for ease of assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, there is indicated generally 5 by the reference numeral 10 a heat exchanger embodying the principles of the present invention.

The heat exchanger 10 includes a casing or housing 12 comprised of an elongated generally cylindrical shell or body'section l4 and end cap members 16 and 18. The body section 14 is formed with a fluid inlet port 20 and a fluid outlet port 22, and is provided with a drain projection 24 and plug 26. Suitably secured to the body section 14 are a pair of mounting flange members 28 and 30 having openings 32 and 34'which are aligned with the fluid inlet and outlet ports 20 and 22. The cap member 16 is provided with a fluid inlet opening 36, a fluid outlet opening 38, and a diametrical axiallyinwardly directed flow divider rib 40 (FIGS. 4 and 5); while the cap member 18 is provided with a drain projection 42 and plug 44.

Secured within the housing 12, as shown in FIGS. 4, 5 and 6, is a core unit 46 comprised of a pair of axiallyspaced radially-disposed circular header plates 48 and 50 each having a plurality of axial apertures 52 formed therethrough. Extending longitudinally between the header plates 48and 50 are four circumferentiallyspaced spacer bars 54 each having a plurality of axiallyspaced notches 56 formed therein. Arranged intermediate of the header plates 48 and 50 are a series of axially-spaced radially-disposed partially-circular baffle discs 58. The baffle discs 58 alternately project in opposite directions, are each formed with three circumferentially-spaced notches 60 which interfit with the adjacent notches 56 in the spacer bars 54, and each have a plurality of axial apertures 62 formed therethrough. The core unit 46 further comprises a plurality of elongated axially-projecting parallel tubes 64 which extend through the aligned apertures 62 and 52 of the baffle discs 58 and header plates 48 and 50.

As shown in FIGS. 1 and 5, the body section 14 is compressed radially inwardly adjacent the header plates 48 and 50 to effect a tight engagement therebetween.' Also, the header plates 48 and 50 are compressed radially inwardly to effect a tight engagement thereof with the tubes 64. In addition, brazing material 66 seals the header plates 48 and 50 to the body section 14 and seals the tubes 64 to the header plates 48 and 50. As indicated by the arrows, one fluid is adapted to enter at the body port 20, follow a circuitous or serpentine path about the tubes 64, and exit at the body port 22; while a second fluid is adapted to enter at the end cap opening 36, flow through the tubes 64 in an overall generally U-shaped path, and exit at the end cap opening 38. During such flow of the two fluids, heat is exchanged or transferred therebetween.

The heat exchanger 10 is fabricated as follows: First, the various components of the core unit 46 are loosely assembled in the general orientation shown in FIG. 5. Preferably, the spacer bars 54 are tack welded to the baffle discs 58, and a suitable fixture is used to hold the components in assembled relation and to facilitate the handling thereof. Then, the loosely assembled core unit 46 is inserted in the body section 14. For ease of assembly, and as indicated in FIG. 7, the body section 14 initially has a substantially uniform diameter throughout its length, the outer diameters of the header plates 48 and 50 initially are slightly less than the inner diameter of the body section 14, and the diameters of the apertures 52 in the header plates 48 and 50 initially are slightly greater than the outer diameters of the tubes 64.

Next, the body section 14 adjacent the header plates 48 and 50 is compressed, crimped or squeezed radially inwardly, for example, from the solid line position shown in FIG. 7 to the dotted line position. ln this manner, a tight engagement is effected between the body section 14 and the header plates 48 and 50. Concur rently, the header plates 48 and 50 are compressed or squeezed radially inwardly whereby the apertures 52 are reduced in diameter to effect a tight engagement thereof with the tubes 64. The described radial compression may be accomplished by any one of a variety of tooling methods: for example, by a pie-section" type of die actuated in a hydraulic press. After the compression operation, the components of the partial assembly are held tightly together; any fixture used for the core unit 46 may be removed, and no fixture is required for the subsequent brazing operation.

Following the compression operation, a slurry of brazing material is applied to the exposed faces of the header plates 48 and 50, and then the partial assemblyi.e., the body section 14 and core unit 46-is heated in a high temperature furnace under a protective atmosphere. As a result of this brazing operation, the brazing material 66 seals the header plates 48 and 50 to the body section 14 and seals the tubes 64 to the header plates 48 and 50.

The materials of the components, the brazing material, the furnace temperature and the furnace atmosphere are subject to a number of variations. Preferably: if the tubes 64 are to be exposed to a corrosive fluid, they are fabricated of stainless steel, and, for economy, may comprise thin wall chrome steel (no nickel) welded tubing; the header plates 48 and 50 are fabricated of sintered iron; and all other parts are fabricated of a mild steel. The use of such materials having a relatively high melting range, and the provision of a tight engagement between the parts being brazed, permit the use of an inexpensive brazing material (one not containing nickel, silver or gold) such as copper. A pure copper brazing material requires a furnace temperature of about 2,050F.; if a small amount of tin is incorporated with the copper, a lower furnace temperature of about l,900 to 1,950F. may be used. When the tubes 64 are fabricated of stainless steel, it is necessary to maintain a dry-hydrogen or a hard vacuum atmosphere within the furnace to obtain good wetting of the tubes. lf corrosion resistance is not essential, the tubes 64 may be fabricated of mild steel which is less expensive than stainless steel and which permits the use of a furnace atmosphere less expensive than the atmosphere required by stainless steel. Also, if desired, the header plates 48 and 50 may be fabricated of mild steel, rather than sintered iron.

After the brazing operation has been completed, the end cap members 16 and 18, and the mounting flange members 28 and 30, are secured, as by welding, to the body section 14.

Operationally, and by way of illustration only, the heat exchanger 10 may be used as an engine oil cooler. In this application, the mounting flange members 28 and 30 are bolted to the side of an internal combustion engine (a portion of which is indicated at 68 e.g. in FIGS. 2 and 3), the flange openings 32 and 34 are placed in communication with the oil passageways of the engine, and the end cap openings 36 and 38 are placed in communication with the liquid cooling system of the engine. Heat from the oil circulating about the tubes 64 is transferred to the engine coolant circulating through the tubes 64.

While there has been shown and described a preferred embodiment of the present invention, it will be understood by those skilled in the art that various rearrangements and modifications may be made therein without departing from the spirit and scope of the invention.

The invention claimed is:

l. A heat exchanger assembly, comprising; a generally tubular housing, a flat header plate adjacent each end of the housing having an original exterior dimension less than the original interior dimension on said housing, a plurality of heat exchange tubes supported in said header plates, said housing having a peripherally compressed portion radially of at least one of said header plates for firmly holding said one header plate in position, said one header plate having a peripherally compressed portion firmly engaged with said peripherally compressed portion of the one header plate.

2. A heat exchanger assembly, comprising; a tubular housing having an original exterior dimension less than the original interior dimension on said housing, a flat header plate adjacent each end of the housing, said header plates being fixed within said housing, said header plates having a plurality of aligned apertures therein, a plurality of heat exchange tubes in said aligned apertures, said apertures having radially inward peripherally deformed portions in firm engagement with said tubes to hold the tubes securely in the header plates.

3. A heat exchanger assembly, comprising; a generally tubular housing, a flat header plate adjacent each end of the housing having an original exterior dimension less than the original interior dimension on said housing, a plurality of heat exchange tubes supported in said header plates, said housing having a peripherally compressed portion radially of at least one of said header plates for firmly holding said one header plate in position, said one header plate having a peripherally compressed portion firmly engaged with said peripherally compressed portion of the one header plate, said header plates having a plurality of aligned apertures therein, said plurality of heat exchange tubes in said aligned apertures, said apertures having peripherally deformed portions in firm engagement with said tubes to hold the tubes securely in the header plates. 

1. A heat exchanger assembly, comprising; a generally tubular housing, a flat header plate adjacent each end of the housing having an original exterior dimension less than the original interior dimension on said housing, a plurality of heat exchange tubes supported in said header plates, said housing having a peripherally compressed portion radially of at least one of said header plates for firmly holding said one header plate in position, said one header plate having a peripherally compressed portion firmly engaged with said peripherally compressed portion of the one header plate.
 2. A heat exchanger assembly, comprising; a tUbular housing having an original exterior dimension less than the original interior dimension on said housing, a flat header plate adjacent each end of the housing, said header plates being fixed within said housing, said header plates having a plurality of aligned apertures therein, a plurality of heat exchange tubes in said aligned apertures, said apertures having radially inward peripherally deformed portions in firm engagement with said tubes to hold the tubes securely in the header plates.
 3. A heat exchanger assembly, comprising; a generally tubular housing, a flat header plate adjacent each end of the housing having an original exterior dimension less than the original interior dimension on said housing, a plurality of heat exchange tubes supported in said header plates, said housing having a peripherally compressed portion radially of at least one of said header plates for firmly holding said one header plate in position, said one header plate having a peripherally compressed portion firmly engaged with said peripherally compressed portion of the one header plate, said header plates having a plurality of aligned apertures therein, said plurality of heat exchange tubes in said aligned apertures, said apertures having peripherally deformed portions in firm engagement with said tubes to hold the tubes securely in the header plates. 